For the first case, 'As Couples' is heard first, so you work As Couples to do
the call 'Once Removed Latch On'. See diagrams below.

Imagine you start herewhere each dancer is a couple

afterOnce Removed Latch On

For the second case, 'Once Removed' is heard first, so you work Once
Removed to do the call 'As Couples Latch On'. Note that, for this case, the
dancers in the set
{,
,
,
}
are on every other plane in both the starting formation and the ending formation.
Similarly, so are the dancers in the set
{,
,
,
}.